Megan Palmer wrote:The fruit resemble guavas which are a member of the myrtle family. However, am unable to identify the exact species.
Try searching myrtaceae fruit images for a match.
We've got a fruit like that here in southern south america that is a myrtacea, very similar fruit (gabiroba, campomanesia spp.), but the leaf pattern and bark are different.
rose apple looks right, but it would help to know the size of the fruit.